The present invention pertains generally to containers made of paperboard or similar materials, and pertains more particularly to liquid tight containers of that type preferably which are non-round in shape having at least one corner with a small radius of curvature.
A number of constructions for round, paperboard, liquid-tight containers are known. Examples are disclosed in U.S. Pat. Nos. 3,369,726 and 3,583,624. Such containers are typically six inches or more in diameter. We have found, however, that when the designs disclosed in the two cited patents or other typical constructions are used for containers having a radius of curvature substantially smaller than about three inches, the result is unacceptable. With smaller radii of curvature, it is difficult or impossible to obtain satisfactory liquid-tight seals with any degree of reliability, and if such a seal can be obtained at all, very high pressures are necessary.
To facilitate the economical storage of products packaged in such containers, it is desirable to provide a reliably liquid-tight container of more angular shape, e.g., a rectangular prism. It is desirable to use radiused corners, rather than right angled corners in such containers. The radius of curvature of such a corner will be far less than the 3 or 31/2 inches typical for round containers. As stated, the known methods of constuction are insufficient for this purpose.